Mogas confessions

GAfuels reader Pete Howell of the Minneapolis area recently posted an article in the newsletter of the Minnesota Wing of Van’s Air Force describing his experiences burning mogas in his Lycoming O-320 – powered RV-9A. Here is an excerpt:

“Why would anyone want to burn anything other than aviation fuel? Well, the current aviation fuel we use, 100LL, is an expensive compromise and actually may be endangered. Despite the name, it has quite a bit of lead (very nasty stuff) in it, and the environmental lobby is working hard to eliminate it, so it may be gone at some point.

Additionally, there is only one source for the lead additive in our avgas, a plant in England, so supply is not guaranteed.

Finally, unless you have a fire-breathing IO-550, your typical low/mid compression Lycoming-style 4 banger really does not need the lead or higher octane! In fact, the lead tends to gunk up the plugs and forms sludge in your oil….”

The full article can be found on pp. 6-8 at this link.  Thanks, Pete!


  1. Sam says

    I find it interesting that he is still not fully flying on Mogas and instead relying on 100LL for take off and landing, the two most critical phases of flight. He also mentions what could have been a vapor lock situation:
    “I switched over to mogas after climbout, the engine stumbled a bit until I hit the aux pump and switched back to the 100LL/mogas mix – then engine ran just fine.”

  2. Jerry Althouse says

    The good folks at Rotax have made it clear that if you regularly burn 100LL in their four stroke engines you will have less chance of reaching TBO than if you burn unleaded mogas. They say that in spite of the negatives associated with ethonal in the mogas. I simply have not been able to locate any ethonal-free mogas here in northeast Texas.

  3. Mack says

    I never understand why people praise nasty leaded gasoline, I would call them brainwashed sissies that have never had to maintain their own vehicles, hands-on.

    Lead sludge that accumulates in the crankcase is no laughing matter. It clogs, not lightly, but in a very heavy, lead-weight, way. In junk yards of the old leaded-gas days, oil pans were heavy with lead sludge, even though a clean oil pan was lightweight, usually made of thin stamped steel.

    Spark plugs don’t even operate when clogged with lead bromides coating the electrodes.

    When I get my 2800 horse Bearcat to fly around, and military money and maintenance, maybe I’ll get 100LL to keep me from detonating a jug, but in the meantime, I’ll keep my low compression, bullet-proof Lycoming, on it’s favorite diet, lead-free Mogas!

  4. Greg W says

    Indeed for those that can use mogas there is very little not to like. Most of the benefits to the engine are actually prescient to the fact that many engines were designed for much less lead than what is contained in 100LL. In the case of some such as the Continental A65 the fuel they were certified with was a no lead gasoline! Kent, I see that the Fuel Club site is shutting down. Despite that please keep pushing mogas in the publications, yours is a voice that airport operators may listen to, much more so, it seems, than those of us who fly less expensive aircraft, and can us mogas.

    • Kent Misegades says

      Thanks Greg – we achieved our goals with the Aviation Fuel Club, but are certainly not slowing our efforts to get mogas onto airfields. Keep watching this blog for more news.

  5. says

    I am in full agreement on this issue. I started using, I call it gas satiation gas as not to confuse anyone, when I bought an STC from EAA for my Colt (Lyc O235) some two years ago. Two annuals and 180 hours later, and my plugs are like new. And guess what, once I got the gunk out of the engine, my oil is almost as clean when I am changing it as it was when I put it in.

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